New Framework for Printerand storage files

Printer cloud System

Android can print now any kind of content over Wi-Fi or cloud hosted service such Google cloud Print. Google gives manufacture as well as developer to add printing API. Client apps can use new APIs to add printing capabilities to their apps with minimal code changes. In most cases, you would add a print action to your Action Bar and a UI for choosing items to print.
New storage Framework allow you develop a client app that manages files or documents, you can integrate with the storage access framework just by using new CREATE_DOCUMENT or OPEN_DOCUMENT intents to open or create files — the system automatically displays the standard UI for browsing documents, including all available document providers.

Low power sensors

Android KitKat 4.4 introduces hardwaresensor batching which is new optimization technique which reduce power consumption.

Tools to beautification your app in new way :)

Full screen immerse mode to give user more space by disabling status bar notification and hardware button introduces in KitKat

Transitions framework will allow you to animate changes to your UI on the fly, without needing to define scenes. For example, you can make a series of changes to a view hierarchy and then have the TransitionManager automatically run a delayed transition on those changes.

Translucent system UI styling and enhance notification access will help you to beautify your app and later will help you to enhance notification access

Graphics and render script improve the performance compare to previous version

Just see comparison chart your self.

Now you can take advantage of RenderScript directly from your native code. A new C++ API in the Android Native Development Kit (NDK) lets you access the same RenderScript functionality available through the framework APIs, including script intrinsics, custom kernels, and more.

New type of connectivity and accessibility are other part which are introduces and improved.

New Media support and Memory analyzer tool are the other. New tool called procstats will help developer to analyze the memory
resources your app uses, as well as the resources used by other apps and
services running on the system.